The present invention relates to high resolution LED printing and, more particularly, to a method and apparatus using lower resolution light emitting diode (LED) bars to achieve a high quality printing capability, wherein 600 spot per inch (SPI) printing can be achieved through specially configured 480 SPI and 268.33 SPI LED bars.
Consumer demand in the printing industry calls for high resolution printing. High resolution printing may be achieved through use of LED bars comprising a large number of closely spaced pixels. Inherent problems with closely spaced pixels include the manufacturing difficulties in manufacturing large numbers of wire bonds and the accompanying necessary electronics to drive the increased number of pixels. In addition, there is a limited amount of space within the printer devoted to the LED bars.
U.S. Pat. No. 4,972,270 discloses a method and system for reproducing facsimile images using a staggered array ink jet print head. The ejecters of the print head are selectively fired to accommodate the requirements of a facsimile transmission.
U.S. Pat. No. 4,916,470, the disclosure of which is incorporated herein by reference, discloses use of an image bar in electrophotographic imaging. The number of pixels on the image bar varies from 200 to 2,000. The image bar may possess one row of pixels or a staggered configuration.
U.S. Pat. No. 5,081,346 discloses a solid state imaging device comprised of a plurality of line sensors arranged in a staggered relationship. The imaging device also consists of an array of rod lenses carrying light from a document to the staggered line sensors. A plurality of blocks house the rod lenses and support the line sensors. The blocks are differently configured to accommodate different imaging needs.
U.S. Pat. No. 5,168,283 discloses a printer head wherein two LED arrays are used. A first LED array is used solely for high quality printing at 300-600 SPI. The second LED array is used for low quality background printing. This arrangement allows for the intermittent use of the high quality LED array, thereby prolonging its life.
U.S. Pat. No. 4,916,530 discloses a multiple beam half tone dot generator system using a plurality of LEDs arrayed in staggered rows. The array pattern achieves a high resolution microdot printing. The LED array is composed of four staggered rows of six LEDs in each row.
U.S. Pat. No. 4,419,679 discloses a recording head for use in an electrostatic printer. The recording head is comprised of four staggered rows of styli. Signals for driving each row of styli are staggered and driven by a random access memory. This arrangement results in a line printing capability that reduces the noise frequency of each line and also reduces spurious discharge across the insulation between the styli to provide better image quality.